Nitrification 
The biological transformation, under aerobic conditions, of different nitrogen compounds as part of the Nitrogen Cycle. Two main processes occur depending upon the original nitrogen compound. Firstly, either Ammonia is transformed to Nitrite and then this is converted to Nitrate, which can be readily taken up by plants. Or, secondly, Ammonium is transformed to Nitrite and then this is converted to Nitrate.
Nitrification Inhibitor
A substance that inhibits soil microbial activity in breaking down ammoniacal-Nitrogen (NH3) to nitrate-Nitrogen (NO3).
Nitrite
This is produced as part of the nitrification process with ammonia (NH3) being converted by oxidation, due to soil bacteria such as the Nitrosomonas species, to nitrite (NO2). Ammonia gas is toxic to plants and therefore the conversion process to nitrites, and then nitrates, is an important part of maintaining a healthy soil.
Nitrogen Assimilation
The uptake and use of nitrogen by a plant.
Nitrogen Cycle
The process of circulating nitrogen between living organisms, the soil and the atmosphere. Nitrogen fixation, Nitrification, Ammonification and Denitrification, are all terms related to the nitrogen cycle.
Nitrogen Cycle, Role of Soil Organisms in the
Soil micro-organisms play a significant role in the nitrogen cycle. They can capture atmospheric nitrogen and fix this within a soil for use by plants, contribute to the process of nitrification to produce nitrates for plant growth, as well as in the denitrification process which removes some nitrogen from a soil and releases it back to the atmosphere when conditions are unsuitable for plant growth.
Node
Any point on a grass stem from which a leaf, rhizome, stolon, or adventitious root may be produced.
Nomenclature
Non-ionic
A surfactant without a charge on its polar head, and do not undergo ionization when dissolved in water. These substances do not change the pH of the soil solution.
Non-Native Species
This is also called Introduced Species. These are species that have often been introduced by human activity to geographic areas which are outside of the species normal range. They are not usually invasive or detrimental to the native species.
They can be categorised as either Archaeophytes (pre-1500) or Neophytes (post-1500), of which there are an estimated 10 species of grass of the former and 50 species of the latter category, for the British Isles (Cope, T. & Gray, A. (2009) ‘Grasses of the British Isles', B.S.B.I. Handbook No.13, p.25).
Most garden and ornamental pl
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